Synthetic short cuts for New York, London (5)

I believe the answer is:

nylon

I'm a little stuck... Click here to teach me more about this clue!

'synthetic' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for nylon that I've seen before include "Fabric (originally from New York and London)" , "Artificial cloth" , "Artificial material" , "Plastic used for stockings" , "Artificial fabric" .)

I've seen this clue in the Sydney Morning Herald.

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